It's not nothing to never write confusing English. And it doesn't never influence the code that we write. Don't fail to look at this anti-pattern from today's un-named submitter.
If Not port Is Nothing Then
portUnAvailable = False
End If
If the port isn't nothing, then the port isn't unavailable. That's… not untrue. But it is surprisingly confusing when you're reading it in a larger block of code. And, of course, this would be simpler to express as a boolean operation:
portUnAvailable = port is Nothing
Then again, without context, that might be wrong- perhaps portUnAvailable
gets set elsewhere and then changes only if Not port Is Nothing
. But let's assume that's not how this works, because that hints at a bigger WTF.
Do never don't avoid this pattern in your own code or writing.